1. Field of the Invention
The present invention relates to a device for adjusting the orientation of screwdown elements for timepieces, and more specifically for crowns having a design or a logo on their end face and in which said design can be oriented as desired.
2. Discussion of the Background
Screwdown crowns are currently used for fitting into watches for the purpose of improving their seal at their winder or control stem. This type of crown has the special feature of being able to assume an unscrewed position, in which the watch can be wound up, the time set etc., and a screwdown position in which the crown is screwed down and locked on a pressed down or screwdown tube in the centrepart of the watch case in order to compress a gasket, thus improving the seal of the watch. The screwdown position is therefore that corresponding to the normal position when the watch is worn and that is more or less always subject to wear of the gasket.
The fabrication and assembly of these screwdown crowns on watch cases are well known. However, the methods of assembly of these crowns are poorly suited to screwdown crowns that bear an inscription or design on their end face, e.g. a logo, a manufacturers' mark or similar mark. In fact, the known methods of assembly do not generally allow the crown to be brought into a specific orientation in relation to the case after they have been screwed down, and this spoils the aesthetics of the case when an inscription is affixed to the end face of the crown. This situation is, of course, unacceptable when these crowns are fitted to luxury and high-quality products.
One solution that allows a crown to be adjusted in a specific position or orientation after being screwed down onto the tube has already been proposed in document EP 1 124 167 A1. According to this document a ring made of shape memory alloy is placed either between the centrepart and the tube or between the crown and the tube. By using the deformation of the ring, in particular reducing its diameter by subjecting the watch to specific temperatures, a temporary clearance can be created between the centrepart and the tube and between the crown and the tube respectively, and this clearance allows angular adjustment of the crown in its screwdown position. A disadvantage of this solution lies in the fact that shape memory alloys are not currently available in the form of bars of small dimensions, and therefore it is difficult and expensive to machine the rings in question to attain the small dimensions required for the applications in question. Moreover, this process is only intended for the initial assembly of the crown by the manufacturer of the watch and not for subsequent adjustment operations for orientation of the crown, which would pose the risk of damaging other parts of the watch that are sensitive to temperature variations.
The document EP 1701225 describes an orientable screwdown crown comprising a head integral to a winder stem and a cover, on which an inscription appears, wherein the head and the cover are rotationally fixed by means of truncated cone-shaped surfaces that are held in contact with one another by means of an elastic element. The angular position of the cover is adjusted by pulling this axially out in relation to the centrepart along the longitudinal axis of the crown. A major disadvantage of this solution is that the rotationally fixed arrangement of the cover in relation to the head is only assured by the frictional forces between the truncated cone-shaped surfaces, and this does not prove to be sufficiently reliable over the service life of a watch and in particular when the compression forces exerted by the elastic element progressively diminish. Moreover, another disadvantage is that it cannot be guaranteed that the same angular position can be obtained in a precise manner, since the angular position can only be determined by successive approximations.
The document EP 1411401 describes a particular crown, which on its upper outside face comprises a substrate that is orientable in relation to a head formed by a central body and a lateral skirt, wherein the substrate is provided with an inscription, and can be rotationally separated from the head of the crown when a pressure is applied against braking means. The disadvantage with this solution is that it is not very robust with respect to shocks, and such shocks can also apply a pressure force onto the substrate and thus reorientate in relation to the body of the crown at an inappropriate time. Moreover, when gripping the crown it is necessary to take numerous precautions to ensure that no pressure is introduced in the direction of the crown if an untimely rotation of the substrate is to be avoided, and this makes usage somewhat inconvenient. Moreover, although indexing means can be provided to position the substrate in predefined angular positions, the inability to grip the substrate correctly makes the adjustment operation very delicate and not necessarily very precise.